The present invention relates to a control circuit for industrial sewing machines including a non-ravel seaming mechanism.
The conventional sewing machines including an automatic non-ravel seaming mechanism have been improved. In one of those, at the start of sewing the rotating speed of a clutch and brake motor is kept at medium speed to actuate a work feed reversing mechanism to carry out non-ravel seaming up to the desired point, and at the end of the sewing operation, the speed of the clutch and brake motor is again decreased down to the predetermined low speed over a certain period. After that, the speed of the clutch and brake motor is increased again up to medium speed to actuate the work feed reversing mechanism.
The above-mentioned sewing machine has the drawback that the time required for the non-ravel seaming is relatively long, for example, 1360 ms is required. The drawback results from the fact that the speed of the clutch and brake motor is decreased down to low speed at the end of sewing.